Multiple-cell molded plastic tray



June 4, 1968 K/DILLER MULTIPLE-CELL MOLDED PLASTIC TRAY Filed May 15, 1967 United States Patent 3,386,608 MULTIPLE-CELL MOLDED PLASTIC TRAY Kenneth Diller, Box 320, East Jordan, Mich. 49727 Filed May 15, 1967, Ser. No. 638,447 2 Claims. (Cl. 220-236) ABSTRACT OF THE DISCLOSURE A multiple-cell molded plastic tray which is nestable with similar trays for shipment or storage, yet the trays are easily separated when desired for use. Each cell has a generally square cross section; and they are connected in parallel rows by means of an integral top edge. These connecting edges define crescent-shaped grooves which provide overflow channels communicating between adjacent cells. The grooves are spaced in the connecting edges such that the trays may be nested wherein the bottom of a groove of an upper tray engages the straight portion of the connecting edge of the tray beneath it. This structure prevents complete nesting of the trays.

Background The present invention relates to multiple-cell molded plastic trays; and more particularly to such trays that may be nested when packed for shipment or storage.

The trays with which the present invention is concerned are advantageously used as individual receptacles for cultivating separate plants and the like, so that each plant may be removed as a unit without having its roots intermingle with roots of adjacent plants.

Molded plastic trays having a plurality of individual cells or compartments joined into an integral unit at their upper edge are being used; however, when these units have been nested by superposing one on the other, it has been very difilcult to separate the trays if even the slightest force has been exerted to squeeze them together. This is due primarily to the fact that the cell walls are tapered,

and they have a generally square cross section which decreases from the top to the bottom of the cell for nesting. Hence, there is considerable contacting surface area between nested cells. This contacting surface area becomes even larger when it is considered that a tray ,may be formed having 96 such cells.

Summary My invention contemplates an arrangement of overflow channels formed in the top edges of adjacent cells in an integral unit such that superposed units are prevented from completely nesting.

The cells have a generally square horizontal cross section, and they are arranged in parallel rows and columns so that the upper edges of the cells will intersect at right angles. In one embodiment, the instant invention provides that the overflow channels of one set of parallel upper edges be located at the middle of the upper edge. The overflow channels in the upper edges running perpendicular to the first set are offset with respect to the middle of the edge so that when a unit is rotated 180 before nesting with another unit, the offset grooves will be out of alignment and engage the straight portion of the edges beneath them.

With this preferred arrangement of overflow grooves and with alternate trays thus rotated, the units may be nested for shipment or storage without fear of their sticking so tightly together that they may not be separated when it is desired to use them.

Other features and advantages of the instant invention will be obvious to persons skilled in the art from the following detailed description of a preferred embodiment Patented June 4, 1968 accompanied by the attached drawing in. which identical reference numerals will refer to like parts in the various views.

The drawing FIG. 1 is a perspective view of a molded plastic tray according to the instant invention;

FIG. 2 is a side section view of the tray of FIG. 1 taken through the sight line 22; and

FIG. 3 is a bottom plan view of a unit of the tray of FIG. 1.

Detailed description Turning to FIG. 1, there is seen two separate trays as nested according to the instant invention. The trays are identical, but as will be clear from subsequent discussion, they have been rotated relative to each other before stacking. The upper tray is designated 8; and the lower tray designated 9.

Each tray includes an arrangement of four separatable, identical units of cells or compartments wherein each unit consists of an integral set of four cells having a generally square horizontal cross section. The units of tray 8 are generally designated respectively as 10, 11, 12 and 13. The units 10-13 are identical in their individual structure, and for brevity, only the unit 10 will be described in detail, it being kept in mind that whatever is disclosed relative to the unit 10 will likewise be true for the units 11, 12 and 13. However, it will be noted that all of the indivilual cells are arranged in parallel rows and columns.

Turning then to the unit 10, it is seen that an upper peripheral rim 14 defines the basic unit. Depending from the rim 14 are four individual cells designated respectively as 15, 16, 17 and 18. Each of the cells 15-18 has a generally square cross section which decreases from the top to the bottom of the cell for nesting when the trays are stacked. To facilitate nesting, adjacent cells are joined only at the top edges. This is illustrated by the upper edge 19 which is integral with adjacent sides of the respective cells 15 and 16.

Similarly, an upper edge 20 is integral with adjacent sides of the cells 16 and 17; an upper edge 21 is integral with adjacent sides of the cells 17 and 18; and an upper edge 22 is integral with adjacent sides of the cells 15 and '18. It will be noted that the upper edges 19 and 21 define a line of intersection with the upper edges 20 and 22. The point of intersection defined by the perpendicular lines formed by the upper edges is identified by reference numeral 23.

Each of the upper edges 1922 further defines a hemispherical groove extending toward the bottoms of the cells and providing an overflow channel for relief when one of the cells has been filled with excess water. These grooves are identified respectively by reference numerals 19a, 20a, 21a and 22a.

As illustrated in FIG. 1, the semicircular grooves 20a and 22a are equidistant from the intersection point 23; and they are located centrally of their respective edges 20 and 22. The grooves 19a and 21a are offset in the direction of the unit 11. That is, the groove 21a is closer to the intersection point 23 than either of the grooves 20a or 22a; and the groove 19a is further from the intersection point 23 than either of these centrally-located grooves.

In FIG. 2 there is shown a vertical section view of the nested trays 8 and 9 taken through one of the centrallylocated grooves. As shown therein, an upper edge 25 defining an offset groove 25a is in line with an upper edge 2.6 defining an offset groove 26a. The lower tray 9 is identical to the upper tray 8. except that it has been rotated 180 so that the unit equalivent to the unit 13 in tray 8 is placed beneath the unit 11. This is identified by refierence numeral 13' in FIG. 1. When thus arranged, it is seen that an upper edge 27 of the unit 13' defines a groove 27a and an upper edge 28 defines a groove 28a. The grooves 27a: and 28a are shifted to the right of the grooves 25:; and 26a when the trays 8 and 9 have been rotated 180 relative to each other and stacked. Hence, the lower edge of the groove 25a of tray 8 will rest on a straight portion of the upper edge 28 of tray 9. In this manner, superposed trays are prevented from completely nesting into a lower tray, and this has been found to be of great advantage in separating the trays when it is desired to use them. What otherwise would be considered a substantial amount of pressure may be exerted on a stack of trays; and, yet, they may be easily separated.

FIG. 3 is a plan view of the bottom of the unit 10 of tray 8; and as is commonly practiced, each of the units comprising a complete tray are separatable from the other units along score lines in their upper rims, as identified by reference numerals 30 and 31 in FIG. 1. As clearly illustrated in FIGS. 2 and 3, the side walls of each of the individual cells defines a decreasing cross section away from its upper rim.

Apertures are provided in the fillets between the bottom and side walls of each cell for drainage purposes. These apertures are identified by reference numeral 33 in the drawing, and they are located centrally of each side wall. As seen in FIG. 3, the centrally located grooves 20a and 22a are intermediate adjacent apertures 33; whereas the offset grooves 19a and 22a are displaced from this intermediate location.

In describing a preferred method of manufacturing multiple-cell molded plastic trays wherein the units comprise 2 x 2 cells, a convention will be made that as an observer addresses the finished tray in an upright position as ejected from the mold, those parallel cells in line with his vision line are columns whereas those transverse are rows. The mold is designed so that a total of six trays may be produced at one time, each tray having eight units of four columns and two rows. Each unit has four cells (two by two). Hence, a total of 192 cells are produced at one time, and they are arranged in 48 columns and 4 rows.

The offset grooves are in the upper edges which separate the columns and the centrally-located grooves are in the upper edges which separate the rows. In the three trays on the left, those grooves which are furthest offset from the intersection point (23 in FIG. 1) of the upper edges of the side walls (corresponding to grooves 19a and 25a in FIG. 1) are closest to the observer. In the three trays on the right, the mold produces units such that these same grooves are farthest from the observer. After the trays have been scored, the three left side trays are simply lifted and nested onto the right side trays. Hence, the offset grooves will be arranged to alternate as shown in FIG. 2. The two nested trays are then moved to the side. By repeating this same motion, a stack is built with as many trays as is desired, and they are arranged in alternating fashion such that no two contacting trays may be completely nested.

It will be noted that units of four which have just been described are about 5% inches square. Approximately this same size has been used for units of 3 x 2 cells, 3 x 3 cells, and 4 x 4 cells. It is further noted that although 180 of rotation of alternate trays has been described and illustrated, a rotation will also be effective to prevent sticking of adjacent'trays.

Having thus described in detail a preferred embodiment of a multiple-cell molded plastic tray which will not stick if properly stacked, it will be obvious to persons skilled in the art that the particular arrangement and number of grooves may easily be changed without departing from the principle of my invention. It is therefore intended that all such modifications and equivalents be covered as they are embraced within the spirit and scope of the appended claims.

I claim:

1. A multiple-cell plastic tray comprising a plurality of cells, adjacent cells joined by an integral, straight upper connecting edge, facing side walls of adjacent cells depending from said connecting edge in spaced relation whereby two of said trays may be nested, said connecting edges defining a groove extending transverse of said edge and including a surface projecting downwardly from said connecting edge and into said spaced-apart side Walls whereby the upper region of adjacent cells joined by said edge communicate with each other through said groove, the groove defined by at least one of said connecting edges displaced from the longitudinal center thereof, whereby trays may be stacked with a groove of an upper tray engaging a connecting edge of a lower tray thereby preventing sticking of said tray when nested.

2. A plurality of trays as set forth in claim 1 wherein said cells have a generally square cross section and are arranged in rows on said tray, said connecting edges defining perpendicular intersecting lines with all of said offset grooves being contained in connecting edges extending in the same direction and with alternate trays being rotated with respect to its adjacent trays to prevent sticking.

References Cited UNITED STATES PATENTS 2,587,852 4/1952 Iahn 22023.6 X 3,009,291 11/ 1961 Blackrnore. 3,195,770 7/1965 Robertson 22023.6

THERON E. CONDON, Primary Examiner.

GEORGE E. LOWRANCE, Examiner. 

